Secondo d urio and giacomo durio



' (No Model.)

I s. & G. DURIO. PROCESS OF AND APPARATUS FOR TANNING. N0. 536,019.

Patented Mar. 19

lllll Q b Q g fzze'emlors'r Scozda 1a Tia NITED. STATES PATENT OFFIQE.

SECONDO DURIO AND GIACOMO DURIO, OF TURIN, ITALY.

PROCESS OF AND APPARATUS FOR TANNING.

SPECIFICATION forming part of Letters Patent No. 536,019, dated March 19, 1895.

Application filed October 16, 1893. Sefla1No.488,304. (NomodeL) Patented in Canada April 27, 1892, No. 42,770, and in EnglendMay 4, 1892, No. 8,469.

To all whom it may concern- Be it known that we, SEooNDo DURIO and GIAooMo DURIO, subjects of the King of Italy, residing at Turin, in the Kingdom of Italy, have invented certainnew and useful Improvements in Processes of Tanning and in Apparatus Therefor, (for which patents have been obtained in the following countries, to wit: in England, No. 8,469, dated May 4, 1892, and in Canada, No. 42,770, dated April 27, 1892;) and we do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to letters and figures of reference thereon, which form a part of this specification.

Our invention has relation to the art of tanning, and it has for its object the provision of means whereby the time required in tanning hides is not only greatly reduced and a final product of superior quality obtained, but whereby the operation of tanning is simplified andthe labor and expense connected therewith are also materially reduced.

We have discovered that abnormally strong solutions of tannin or tannic acid can be employed in tanning without danger of the leather becoming case-hardened, burned, or otherwise injured, provided the hides are kept in constant more or less violent motion, or subjected to a constant more or less violent fulling operation, as for instance in a tumbling mill.

By our process the largest and heaviest hides can be tanned in about thirty hours, hides of less size and weight can be tanned in about twenty hours, while hides such as those of sheep, goats, lambs, or kids, can be tanned in about four hours. i V

When We speak of abnormally strong tannin or. tannic acid solutions we mean solutions of a strength not less than 6% Baum equal to 48% barkometer equal to '65" tannometer (French), thoughwe prefer to use a solution of a strength of from about 8-Baum equal to barkometer equal to 8O tannometer (French), to 20 Baum equal t615'0 barkometer equal to 200 tannometer (French), the strength of the solution being kept uniform during the entire process of tanning by the addition of tannin or tannic acid.

In carrying out our invention we prepare a solution of tannin or tannic acid of the strength hereinbefore referred to, which is poured into any suitable vessel to which motion may-be imparted in such a manner that the hides will be subjected to a fulling or tumbling action, as for instance, a. revoluble cylindrical vessel, or a vessel of angular form in cross section, after Which the hides are introduced, and the vessel'is set in motion, which is continued until the charge of hides is tanned, except for such brief periods as are necessary to test the strength of the solution and reconstitute the same to its original strength, or preferably, to a strength slightly above its original strength. Thus, for instance, in a vessel of a diameter of two meters and of the same length, from about five hundred to six hundred kilos of hides canbe tanned at one operation, and if the hides are large and heavy the strength of the solution may vary from 8 Baum equal to 60 barkorneter equal to 80 tannometer (French) to 20 Baurn equal to 150 barkometer equal to 200 tannometer (French), the quantity of solution being-sufficient to nearly half fill the vessel before the hides are introduced. The vessel is now revolved at a speed which may be varied within certain limits, the aver- .age speed best suited being about ten revolutions per minute. From time to time the liquor is tested and reconstituted to its original strength, or slightly above its original strength, so that when the operation of tanning is completed, which for large and very heavy hides does not exceed thirty hours, the liquor in thevessel will be of the strength required for a fresh batch of hides.

For smaller hides, such as those of sheep, goats, and the like, the'strength of the liquor may be reduced to about 6% Baum equal to at8i barkometer equal to tannometer (French), if desired, but we prefer to use liqnor of about 8 Baum equal to 60 barkometer equal to tannometer (French), though this may be increased to 20 Baum equal to 150 barkometer equal to 200 tannometer (French), without the least injury to the hides, the time required for tanning being from two to four hours.

For hides of weight intermediate of the heavier and the lighter hides, as cow hides, calves hides, 850., the time required is about twenty hours and less, according to weight of the hides, the strength of the liquor beingthe same as above stated,or from 8 to 20 Baum.

We are aware that it has been proposed to employ so-called strong solutions of tannin or tannic acid, strong in comparison with the strength of the liquor theretofore employed. For instance, it has been proposed to use a tannin solution of a strength of from 5 to 10 barkometer, instead of a solution of the usual strength of about 7? barkometer, and to increase the strength of the solution from 3 to 4; barkometer at three or four different times, so that a final strength of about 26 barkometer would be reached, the time required for tanning sheep skins being three or four days, calf skins eight days, and heavy skins or hides from forty to forty-five days, the hides being frequently handled during the process. It has also been proposed to tan hides in socalled strong liquors, but it has been found impracticable for the ,reason that the latter became case-hardened and otherwise injured, to avoid which, protective agents have been used, the hides being subjected to the action of a weak liquor for several days, then dried or partially dried; and to protect the grain side of the leather against the too rapid action of the stronger liquor, grease or thick dubbing has been applied thereto. In this process it is also necessary to handle the hides more or less frequently, While the duration of the operation of tanning is only one-fourth less than that required by the older processes.

In our process of tanning the hides do not undergo any special preparation, except depilation, swelling or raising, removal of flesh and fat, and washing, 1'. e., the usual preparations necessary to place the hide in proper condition to be acted upon by the tannic acid. WVe employ neither grease nor dubbing nor chemicals of any kind, either before or during the process of tanning, for which purpose we use any suitable tannic acid, preferably as pure a tannic acid as is obtainable, the hides being introduced into the revoluble vessel, and not again handled until the operation of tanning is completed, after which the leather is treated in the usual manner.

We are aware that it is not new to subject hides to the action of weak liquors and to a fulling or tumbling action simultaneously, and we do not desire to claim this combined action broadly. We believe, however, that we are the first to combine a fulling or tumbling action with the use of an abnormally strong liquor in the process of tanning, and that the results so obtained cannot be obtained by any other process within our knowledge.

If desired, the hides may in the start be subjected to the action of a weak liquor, as forinstance,aliquor of about 3 or 4 Baum, the strength of density of the liquor being gradually increased to from 8 to 20 Baum. There is, however, no special advantage in do- .may be varied if desired.

ing this, and although the results are the same, yet the time required for tanning a batch of hides is increased, and for this reason we prefer to start the operation with what we consider an abnormally strong solution, the strength of which is maintained uniform from the beginning to the end of the operation, so as to leave the liquor in a condition for use with a fresh batch of hides. After the liquor has been used about six or more or less times, it is filtered to remove therefrom foreign matter.

Any suitable apparatus may be employed in carrying out our invention, yet such ap* paratus should be provided with special devices for facilitating the reconstitution of the tanning liquor from time to time, and particularly for discharging the gases evolved during the operation of tanning, and to these ends we have invented the apparatus shown in the accompanying drawings, in which- Figure 1 is a side elevation of an appara tus especially adapted for carrying out our invention, and Figs. 2, 2, 2" and 2, are detail views thereof.

Similar symbols refer to like parts wherever such may occur in the above described figures of drawings.

T,indicates a cylinder or cylindrical vat or barrel provided with journals i, t, revoluble in suitable bearings c, c on convenient supports therefor as rails a. and a, Fig. l. The journals 17,25 are hollow and made of a metal not attacked by the tannic acid, as bronze, for instance, in practice, and for convenience of operation we prefer to use a revoluble cylinder T of such a capacity as to hold from five hundred to six hundred kilos of hides, and leave sutficient room for keeping the hides in motion and subjecting them to a somewhat violent tumbling action. A cylinder of an exterior length of two meters and of a similar exterior diameter will fulfill these conditions, though these dimensions The cylinder is provided with a charging and discharging hole closed by a suitable gate P, and as it is desirable to close the same as rapidly as possible after charging, the said gate is constructed as more clearly illustrated in Figs. 3 and 3, the latter figure showing a section of the gate and a portion of the cylinder about on the line m-a: of Fig. 2.

The gate P is provided with a hand hold 19 and with two strong hinges 20 and 21, so as to turn downwardly. To the cylinder are bolted above and below the charging and discharging opening strong bolt straps l3 hav ing belt loops or eyes 14. for the reception of the ends of the bolts 15 and 16, which are slightly arched and have each two screwthreaded perforations for the locking screws 1717 and 18-18, respectively, that have bearing on the gate P and force the same tightly into the opening in the cylinder. In

IIO

order to obtain a tight joint the opening in the cylinder, as well as-theedges of the gate P are made to taper inwardly, a construction that is well known, and wherebya fluid tight joint can be obtained without a packing, though, if desired, a suitable packing may be used.

A modificationof the means for closing the charging opening is shown in Figs. 1, 3 and 3 the gate being provided with forked lugs n, adapted to receive locking bolts 37hinged to the cylinderT by means of which and the nuts 42' a fluid tight joint may also be obtained. Rotation is imparted to the cylinder T by means of a toothed rim D thereon and a pinion d in gear therewith, and secured to a transmitting shaft 0, that carries two fast pulleys p, p and an intermediate loose pulleyp for purposes well understood, said trans-' mitting shaft 0 being driven from any suitable prime motor. The cylinder T is further provided with a purge cock '0 and with a test cock 6, for the purpose of withdrawing the tanning solution and testing its strength, so

that it may be restored to its original or to slightly greater strength, which can readily be done when the quantity'of liquor in the cylinder is known.-

The concentrated or strong liquor to be supplied to the cylinder from time to time is contained in a reservoir R, whose form is immaterial so long as the interior cross sectional area is uniform from top to bottom. A float fis employed as a means for recording or indicating the quantity of liquor withdrawn from reservoir B, through pipe 1. This float is connected by a cord 24 running over guide pulley b h and around a suitable transmitting pulley of an indicator 2' of any usual or preferred construction.

A pipe 1 connected with the reservoir R at the bottom thereof has astop cock 2, and below the same two branches, each provided with a stop cock, 3 and 4 respectively, one of said branches being connected with the hollow journal or trunnion t of cylinder T, while the other is connected to a pipe 6 whose object is to provide means for introducing liquor into the cylinderT by means of a pump,'not shown, which can be readily done by opening stop cocks 3 and 4 and closing stop cock 2. Said pipe 6 may also be used for supplying liquor to reservoir R by opening stop cocks 2 and 3 and closing stop cock 4:. Furthermore, if it were desired, the pipe 6 could be used either -for forming a partial vacuum in vessel T, or

for establishing pressure therein by a suitable manipulation of the stop cocks 2, 3 and 4, and with the aid of a suction or force pump, as will be readily understood. It is, however, expressly declared that we do not provide the pipe 6 as a means for producnig a partial vacuum or establishing pressure in cylinder T as they are foreign to our invention, and we merely makemention of these facts with a view to fully describe the various results that can be obtained by the arrangement of pipes and stop cocks described.

In carrying out our process, and particularly that part thereof which relates to the reconstitution of the tanning liquor to its original strength, it is, we may say, absolutely necessary to provide a gas vent, for the reason that in the operation of tanning and simultaneous fulling or tumbling, considerable quantities of gases are evolved which eventually might exert such a pressure as to prevent the feeding of fresh liquor from reservoir R to cylinder T. To avoid this we provide the necessary means, which consist of a receiver B, preferably spherical, connected with the cylinder T through the hollow journal and a pipe provided with a stop cock 7, said receiver being also provided with a purge cook 12, a pressure gage 10, a level indicator 11, a safety valve 3 and a vent or gas escape pipe 9 provided with a stop cock 8. Whenever fresh liquor is supplied to the cylinder T, the stop cock 8 is opened, thereby allowing any gas in said cylinder to escape.

The ventpipe 9 is preferably extended above the cylinder T to prevent any possible escape of liquor under such pressuresas may exist in said cylinder, and inasmuch as the latter is never more than half full of liquor, an escape of such is not to be apprehended.

During the operation of tanning the stop cock 7is open, so that by means of the apparatus described the said operation of tanning may be observed.

We claim the following material advantages as theresult of our invention: The operation of tanning takes place in one and the same vessel without interruption, except as noted, during which operation the hides rer 05 use no chemicals or other materials except tannin or tannic acid; and, finally, the time required for tanning is shortened from days to a few hours."

Having thus described our invention, what we claim as new therein, and desire to secure by Letters Patent, is

1. In the art of tanning, the improvement which consists in subjecting the hides, after the preliminary operation thereof for tanning, to the immediate action of an abnormally strong tanning liquor and at the same time subjecting them to a fulling or tumbling action for the purpose set forth.

2. In the art of tanning,-the improvement which consists in subjecting the hides, after IIO the preliminary preparation thereof for tan- I and subjecting the hidesduring said opera- 1 o chamber both with respect to the receiver T, and the air, as and for the purpose set forth. In testimony that We claim the foregoing as our invention We have hereto signed our names in the presence of two witnesses.

SECONDO DURIO. GIACOMO DURIO.

Vitnesses:

EUGENIO G. B. CORSETTOR, G. ERMANNO VIVARELLIS. 

